[67malibu]

If it's still shifting fine otherwise, it may not be that the trans is about to eat itself. I've had numerous trannies start slipping some under WOT (powerglides and turbo350s) and still shift fine and live long lives but 700R4s are weaker and may be an exception. Alot of times this can be an adjustment issue that I do not know how to tackle with a 700R4 (the bands can easily be adjusted on a powerglide to resolve this.) If it does eat itself, the only experience I have is buying a stock rebuild from Autozone. It was done by Accurate. Alot of these other outfits wanted $1500+. I got a 700R4 for my '88 K1500 for $950 and it's been behaving just fine for about five years being a daily driver and towing a trailer once a week. If you want better than stock, I would agree with going with a trusted name such as TCI. Otherwise, see if there's a good shop around. I found one too late that everybody I know is really satisfied with that would have rebuilt it for me (install and all) for $1100 and guaranteed it for as long as I own it.